His biography of the journalist and broadcaster Malcolm Muggeridge, published this Wednesday, reveals a different Ingrams from the professional denigrator of Private Eye and the Oldie; this is Ingrams as admiring disciple.
The oddest thing about his departure from the habits of a lifetime is that Muggeridge's character provides plenty of opportunity to explore what are usually Ingrams' pet targets - hypocrisy, pedantry and downright obnoxiousness. To many people, Muggeridge was an appalling person: first a hard-drinking lecher, and later in life a gratingly evangelical Christian who became the mainstay of the Sunday evening God spot on television.
Ingrams, however, found much to inspire affection and readily acknowledges that Muggeridge was his mentor and father figure for more than 20 years. "I formed a bond with Mugg instantly," says Ingrams. "He started talking and never stopped as far as I was concerned."
They first met in 1963, when Ingrams was 26 and newly editor of Private Eye, and Muggeridge was 60. It was a significant year for Muggeridge, the one when he gave up drinking, smoking and adultery on a grand scale and became a professional pontificator on religion and morality. Friends and enemies alike found his transformation hard to swallow, but Muggeridge at his most charming was witty and insightful, and his oratorical skills soon brought him international fame as a television personality.
Ingrams had two advantages in his friendship with Muggeridge. One was that he had not known him as the drunken groper who once outraged his hostess by climbing uninvited into her bed while her husband slumbered an inch away. The other was that Ingrams shared Muggeridge's interest in religion, and particularly Catholicism. More significantly for thousands of readers of Private Eye and later the Oldie, Ingrams learnt the art of satire at Muggeridge's knee.
"It was Malcolm who taught me to be distrustful of all politicians, to laugh at them," says Ingrams. "His anarchic spirit was very seductive. I was only slightly like that then, but after the Profumo scandal that year gossip came out into the open and Mugg was in his element."
Muggeridge had been editor of Punch for five years, until 1957, when he was sacked for persistent bad taste and unwarranted jokes at the expense of the Royal Family.
"That in a way made the advent of Private Eye possible," says Ingrams, "because after Mugg Punch reverted to type and went into a long decline."
For Ingrams, Muggeridge was the father of present-day satire, an accolade that perhaps excuses some of his later God-squadding excesses.
"I don't think his switch to religion was hypocritical," says Ingrams. "He always had a religious temperament, but he thought that so long as he was living the kind of life he was it would be hypocritical on his part to belong to a church of any kind."
Muggeridge also had a talent for rewriting his life, which was handy because it allowed the famously puritanical Ingrams to ignore the explicit sexual content of his diaries ("fairly depressing reading") and use Muggeridge's more sanitised memoirs published in the early 1970s.
"It's true someone who hadn't known him could have made him look like, I don't know what - a sort of monster," concedes Ingrams. "It would have been very easy if you placed too much emphasis on certain things. I wanted to get the balance right, which is very difficult."
Balance and sympathy are surely words that have not hitherto had a place in the Ingrams' vocabulary. Does this new, gentle approach somehow reflect his current domestic happiness with Deborah Bosley, 27 years his junior? After the shock and vitriol of his wife Mary's sudden departure in 1991, Ingrams is now divorced and, he says, reconciled to the very public collapse of his 30-year marriage.
He looks content. The familiar schoolboy sweater is still there, but his tufty hair is cropped shorter than before, neater and, dare one say it of Britain's leading fogey, even a touch more up-to-date. He fiddles with his glasses as he talks, carefully lining them up against the headline of the newspaper he is leaning on. His silences seem less morose than those of legend and more the considered pauses of a careful speaker.
He is 57 now. His childhood does not seem to provide happy memories. He was the second of four boys, and spent his early years living in Aberdeenshire with his mother's family. After the war, the family moved to Cheyne Row in London. He has always been close to his mother, now 87, but his father is a slightly mysterious figure, a "freelance merchant banker" who was often away and who died when Ingrams was 15. "I never had a father that I knew, so I have always had father-figures in my life," he says. The writer Claud Cockburn, who introduced him to Muggeridge, was an early influence.
Ingrams was desperately homesick at prep school, but things looked up when he went to Shrewsbury and met his fellow founders of Private Eye, Willie Rushton, Christopher Booker and Paul Foot.
He met his former wife at Private Eye, where she was a secretary. They have two grown-up children, Margaret and Fred. The split was unpleasant and high-profile. Mary accused him of having an affair with an American journalist, which he denies, and kicked him out, before moving out herself to their holiday home in Rye. She gave her story, or her side of it, to Nigel Dempster, an old enemy of Ingrams', and besieged the Eye offices with abusive faxes and phone calls. Ingrams and Deborah, who is also a writer, are now living in the family home.
Whether or not it is domestic bliss that has drawn his teeth, supportive biographies could become an Ingrams industry in future. He would like to give the same appreciative treatment to the comedian Peter Cook, his old friend and collaborator and the controlling shareholder in Private Eye until his death earlier this year.
"I would like to do a biography because as with Mugg I could present a sympathetic picture. I feel that in the end Peter is going to be blackened."
It sounds as though Ingrams does not subscribe to the popular notion that Cook wasted his talents by largely dropping from view after his split with Dudley Moore. "It's true in a way, but the salient fact about Peter is that he was an alcoholic, which is something that nobody ever says. It was something he shared with his friend Barry Humphries. When I knew them first in the Sixties, they were these two drunkards. Barry joined AA and Peter tried to, you see, he went to clinics and things. He certainly made efforts at various times during his thirties. I don't know whether he gave up trying, but I'd be interested to find out. He was a very private person, Peter, he never confided very much."
Again there is common ground between the would-be biographer and his subject. Ingrams was himself a heavy drinker before giving up on the advice of his doctor at the age of 30. "Perhaps I had a bond with Peter because I knew what he was up to," he says. "I think if it hadn't been for drink he would have gone on writing and being on television. And he wouldn't have fallen out with Dudley Moore because that was due to drink - Peter would go on stage drunk and start improvising and Dudley didn't know what was going on."
A life of Cook would at least be timely. The Muggeridge biography has had such a long gestation since first being commissioned in 1982 that Muggeridge is now rather a forgotten figure. Ingrams puts this down to the ephemerality of television, but much of Muggeridge's writing has not lasted either. Only three of his 26 books are still in print and few under 35 remember his ubiquitous broadcasting days, when he performed as what one producer called "Christianity's most bizarre exhibitionist". He died in 1990, but for at least six years before that he had been in intellectual decline, probably, thinks Ingrams, with Alzheimer's disease. Ingrams claims to be pleased about his subject's disappearance from public consciousness: "It meant I could make a case for him on his merits, rather than as the very famous man he once was," he says.
It is typical of Ingrams, with his proclaimed contempt for all aspects of youth and modern life, that he should choose to focus on a man whose stance as a crusading Christian and moral arbiter made him an anachronism even in his own day. "I think of Muggeridge and myself as conservative, Christian and anarchist," says Ingrams. "I also share with him the view that we live in a declining civilisation which is quite similar to various other decadent civilisations before some kind of totalitarianism took over." Muggeridge was convinced all his life that the Commies were coming. The Ingrams nightmare includes the possibility of an extreme right-wing dictatorship - he thought he detected signs of the appropriate shift in mentality in Alan Clark's diaries and their author's idolisation of Margaret Thatcher.
In religion, too, Ingrams and Muggeridge are pretty much of one mind. Muggeridge converted to Catholicism in 1982, when he was 79. Ingrams thinks he will probably make the same move "eventually" (although technically he does not need to convert; his Catholic mother, just to be on the safe side, had her four sons baptised as both Catholics and Anglicans). For life to imitate biography completely, all that remains to be fixed is a future for Ingrams in religious broadcasting.
It is a curious juxtaposition that these professional sneerers and attackers of establishment pomposity should also be religious. (Ian Hislop, Ingrams' successor at Private Eye, is also an occasional church-goer.) Somehow the natural pessimism of the satirist does not seem to sit easily with the necessary optimism of religious faith.
Ingrams practises as a high-church Anglican, chiefly through playing the church organ. He is drawn, among other things, to what Graham Greene called the "magic" of the Catholic church, the saints, rosaries and miracles. A strangely sentimental taste for the Ingrams we thought we knew.
An Ingrams biography of Cook would contain more surprises. Not even that comic hedonist would escape a spiritual dimension at the hands of Ingrams, who, it seems, is fast raising religion from an interest to an obsession.
"I would define Cook as conservative, Christian and anarchist too, like Malcolm and myself, except that he would deny the Christian bit. But he was obsessed by religion. If you look at his jokes with Dudley Moore, they were always going on about St Paul and God. He was very bothered by it, in a way that I suppose a lot of people are," says Ingrams.
If Ingrams is right, that makes two old men (or three counting Ingrams), iconoclastic outsiders all their lives, drawn in their last years to religion.
"My own faith is not always very strong," says Ingrams. "I find Graham Greene a much more appealing figure than Malcolm because of his air of great uncertainty. A priest friend of Greene's told him that continuing doubt was actually a religious state of mind - which is very reassuring."